Real-world outcomes in metastatic HR+/HER2-, HER2+and triple negative breast cancer after start of first-line therapy

Aim: We evaluated outcomes of first-line (1L) treatment of metastatic breast cancer (mBC) by biomarker subtype in the community setting over the last decade. Methods: Eligible patients (N = 1,518) were female, >= 18 years, diagnosed with mBC 2010 or later, had documented HR+/HER2-, HER2+, or triple negative breast cancer (TNBC); and initiated 1L therapy. Kaplan-Meier and Cox methods were used to evaluate 1L real-world progression-free survival (rwPFS) and overall survival (OS) from start of 1L. Results: TNBC was diagnosed at an earlier stage and had higher tumor grade at initial diagnosis. 1L rwPFS and OS from start of 1L were shorter for TNBC than HR+/HER2- or HER2+. Conclusion: Overall prognosis for patients with metastatic TNBC remains poor, and new therapies are needed to improve clinical outcomes. Plain language summary What is this article about?This study looked at how well women with metastatic breast cancer did after starting treatment. It compared three groups. The first group had tumors that respond to hormone therapy. The second group had tumors that respond to treatment that works on a specific protein. A third group had tumors that don't respond to either of those - called triple negative. The study looked at women 18 and older who had metastatic breast cancer in 2010 or later. They had all been treated at a community oncology practice. We looked at how long it took for the cancer to get worse, and how long until patients died, for each of the three groups. What were the results?There were 1518 patients in the study. Most (62.5%) were in the group that responds to hormone therapy. The rest had tumors that respond to treatment that works on the specific protein (23.4%), or had triple negative tumors (14.1%). Patients with triple negative tumors were diagnosed earlier, but they had worse tumor characteristics. They also had shorter time until their cancer got worse, and they did not live as long, compared with the other groups. What do the results of the study mean?This builds on other studies by showing that, even in a modern era, outcomes are poor for patients with triple negative breast cancer. It shows that new treatments are needed for patients with triple negative breast cancer.